Competitive cations
Since Cu and Zn are preferentially
bound to soil particles, higher Cu/Zn content is advantageous for Cd removal
because it often means Cd is more bioavailable.
The addition of Calcium (Ca2+)
to soil reduces Cd bioavailabilty by increasing pH and competing for Cd
on root absorption sites (Cieslinski, 1996). Therefore, addition of Ca
as a fertilizer should be avoided.
Manganese (Mn) also competes
with Cd for plant uptake (Kabata-Pendius and Pendius, 1992). Furthermore,
Clijsters and Van Assche (1985) demonstrated that the effect on plant metabolism
could be reversed by Mn.
It has been suggested that Zn
might compete with Cd for uptake into the plant because of their structural
similarity. Lombi, et al. (1999) showed that Cd and Zn uptake are independent,
suggesting two different mechanisms for uptake.
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